Toxicity and Antifeedant Activity of Selected Plant Extracts Against Larval Obliquebanded Leafroller, Choristoneura rosaceana (Harris)~!2008-11-07~!2009-09-30~!2010-02-10~!

Abstract

Several plant extracts were evaluated against obliquebanded leafroller larvae to determine potential toxicity and antifeedant effects. Two of the plant extracts exhibited contact toxicity; the LC 50 value of Humulus lupulus extract against 3 rd instar larvae was 24.5 μg / insect. In a no choice context, larval survivorship was reduced 23-57 % after feeding on a meridic pinto bean diet treated with the extracts. Furthermore, average female and male pupal weight was reduced for lea-frollers that fed on diet treated with each of the individually-tested extracts at a 4 % concentration (w/w). Incorporation of Bifora radians and H. lupulus into diet deterred larval feeding at a 1 % concentration by weight. H. lupulus and Arctium lappa extracts were deleterious to larvae in each of the bioassay methods conducted, exhibiting toxic, developmental, and antifeedant effects. These two extracts may be promising candidates for further development as botanical insecticides that could potentially substitute broad-spectrum synthetic neurotoxins for leafroller control. INTRODUCTION The Obliquebanded leafroller, Choristoneura rosaceana (Harris), is a tortricid moth with a wide host range including woody plants in the Rosaceae as well as Ulmus, Populus, Quercus, Betula, and Tilia [1]. Depending on the geographic region and climate, there are one or two generations of adults per year with an overwintering second or third-instar larval generation [2]. The polyphagous larvae are primarily foliage feeders, but are also known to feed on and damage apple fruit [3].